Grain boundary strengthening and precipitation strengthening can increase the strength of a material by several times, but this benefit usually leads to a sharp loss of ductility. In this work, a thermomechanical processing method combining cryo-rolled and single-step annealing was proposed to obtain a strength–ductility balance Al5Ti2.5Fe25Cr25Ni42.5 high-entropy alloy (HEA). The cryo-rolled HEA is comprised of HCP- and BCC-martensite induced by deformation, along with a residual FCC matrix. After single-step annealing in 900 °C, a structure with L12 and BCC double precipitates was formed through partial recrystallization and phase transformation to obtain excellent mechanical properties. The Phase-field crystal (PFC) method was used to confirm that the plasticity of high-angle grain boundary (HAGB) system is better than that of low-angle grain boundary (LAGB) with high-density dislocation system. The excellent mechanical properties of Al5Ti2.5Fe25Cr25Ni42.5 HEA with ultimate tensile strength of 1214.4 MPa and fracture strain of 25.8% at room temperature were obtained. EBSD and TEM characterizations show that the excellent mechanical properties are mainly derived from the favorable coherent spherical L12 precipitation and the high number density of annealing twins.

中文翻译：

---

Al5Ti2.5Fe25Cr25Ni42.5 高熵合金的低温轧制和退火介导的相变：实验、相场和 CALPHAD 研究


晶界强化和析出强化可以将材料的强度提高数倍，但这种好处通常会导致延展性急剧损失。在这项工作中，提出了一种低温轧制和单步退火相结合的热机械加工方法，以获得强度-延展性平衡的 Al5Ti2.5Fe25Cr25Ni42.5 高熵合金 （HEA）。冷冻轧制的 HEA 由变形诱导的 HCP 和 BCC 马氏体以及残留的 FCC 基体组成。在 900 °C 下单步退火后，通过部分重结晶和相变形成具有 L12 和 BCC 双沉淀物的结构，以获得优异的机械性能。采用相场晶体 （PFC） 方法证实，高角度晶界 （HAGB） 系统的塑性优于具有高密度位错系统的低角度晶界 （LAGB）。Al5Ti2.5Fe25Cr25Ni42.5 HEA 在室温下具有优异的力学性能，极限拉伸强度为 1214.4 MPa，断裂应变为 25.8%。EBSD 和 TEM 表征表明，优异的力学性能主要来自良好的相干球形 L12 沉淀和退火孪晶的高数密度。